U.S. patent number 5,580,370 [Application Number 08/051,706] was granted by the patent office on 1996-12-03 for total heat energy exchanger element preventing a transfer of odors and method of manufacturing same.
This patent grant is currently assigned to Kabushiki Kaisha Seibu Giken. Invention is credited to Toshimi Kuma, Noriaki Shirahama.
United States Patent |
5,580,370 |
Kuma , et al. |
December 3, 1996 |
Total heat energy exchanger element preventing a transfer of odors
and method of manufacturing same
Abstract
Adsorbents are used whose equilibrium isotherms for adsorption
show no rapid rise in relative humidity more than 40% and whose
equilibrium isotherms for adsorption and desorption show no
hysteresis phenomenon and in which adsorbed humidity does not cause
capillary condensation, for example, A-type or RD-type silica gel
or hydrophilic zeolite. Adhesive or binder is applied on the
surface of a metallic sheet, a plastic sheet or a ceramic fiber
paper, and particulates of the above-mentioned adsorbents are fixed
on or in it to get a total heat energy exchanger material. The
total heat energy exchanger material is corrugated and laminated to
obtain a total heat energy exchanger element. When outer air or
return air contains various odorous gases, these odorous gases can
be mostly prevented from transferring into supply air through the
total heat energy exchanger. When particulates of the
above-mentioned adsorbents and chemical blowing agents are mixed in
adhesive and said chemical blowing agents are made to blow by
heating, the part of adsorbent particulates buried in the adhesive
layer can also function as adsorbent through communicating pores
and thus total heat energy exchange efficiency can be
increased.
Inventors: |
Kuma; Toshimi (Fukuoka,
JP), Shirahama; Noriaki (Ohnojo, JP) |
Assignee: |
Kabushiki Kaisha Seibu Giken
(Fukuoka-ken, JP)
|
Family
ID: |
15644897 |
Appl.
No.: |
08/051,706 |
Filed: |
April 26, 1993 |
Foreign Application Priority Data
|
|
|
|
|
May 3, 1992 [JP] |
|
|
4-157222 |
|
Current U.S.
Class: |
96/154; 428/116;
428/182; 428/186; 428/331; 428/402; 96/125 |
Current CPC
Class: |
B01D
53/02 (20130101); B01D 53/04 (20130101); B01D
53/06 (20130101); B01D 53/261 (20130101); B01J
20/28023 (20130101); B01J 20/2803 (20130101); B01J
20/28033 (20130101); B01J 20/28045 (20130101); F24F
3/1423 (20130101); B01D 2253/106 (20130101); B01D
2253/108 (20130101); B01D 2253/3425 (20130101); F24F
2203/1036 (20130101); F24F 2203/1048 (20130101); F24F
2203/1068 (20130101); F24F 2203/108 (20130101); F24F
2203/1096 (20130101); Y10T 428/2982 (20150115); Y10T
428/24694 (20150115); Y10T 428/259 (20150115); Y10T
428/24727 (20150115); Y10T 428/24149 (20150115) |
Current International
Class: |
B01J
20/28 (20060101); B01D 53/04 (20060101); B01D
53/26 (20060101); B01D 053/02 () |
Field of
Search: |
;428/116,117,182,186,283,344,402,407,457,905 ;96/125,154 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Adsorption Surface and Porosity, S. J. Gregg and K. Su Sing,
Academic Press, London, 1967, p. 160. .
Hand Both of Chemistry Edited By The Chemical Society of Japan,
Applied Chemistry Parts, Part I, Maruzen pp. 256-257, Oct. 1986.
.
The Chemistry of Silica, pp. 488-492 (1979) Ralph H. Iier. .
Principles of Adsorption and Adsorption Processes Douglas M.
Ruthven, pp. 48 & 49 (1984)..
|
Primary Examiner: Bell; James J.
Attorney, Agent or Firm: Staas & Halsey
Claims
What is claimed is:
1. A total heat energy exchanger element preventing the transfer of
odors, comprising;
a sheet;
an adsorbent on said sheet, said adsorbent having:
equilibrium isotherms for adsorption demonstrating no rapid rise in
relative humidity of more than approximately 40%, and
equilibrium isotherms for adsorption and desorption demonstrating
no hysteresis phenomena which occur where the adsorbed humidity
shows capillary condensation as a main component of the adsorbent:
and
a corrugated material adhered to the sheet.
2. A total heat energy exchanger element as in claim 1, wherein
said sheet is laminated and formed as a honeycomb structure.
3. A total heat energy exchanger element as in claim 2, wherein
said adsorbent is rigidly adhered with an adhesive to the surface
of said sheet.
4. A total heat energy exchanger element as in claim 2, wherein
said adsorbent as particles is rigidly affixed with a binder
impregnated into said sheet.
5. A total heat energy exchanger element as in claim 1, wherein
said adsorbent is selected from the group consisting of A-type
silica gels, RD-type silica gels and hydrophilic zeolite.
6. A total heat energy exchanger element as in claim 4, wherein
said adsorbent comprises particles in the ratio of 5-30 g per 1
m.sup.2 sheet area.
7. A total heat energy exchanger element as in claim 1, wherein
said sheet is selected from the group consisting of metal, plastic
and ceramic fiber paper.
8. A total heat energy exchanger element as in claim 3, wherein
minute communicating pores are formed in the adhesive layer.
9. A total heat energy exchanger element as in claim 3, wherein
said adsorbent comprises particles in the ratio of 5-30 g per 1
m.sup.2 sheet area.
10. A total heat energy exchanger element comprising:
a sheet;
an adsorbent, located on said sheet, said adsorbent having;
equilibrium isotherms for adsorption demonstrating no rapid rise in
relative humidity of more than approximately 40%, and
equilibrium isotherms for adsorption and desorption demonstrating
no hysteresis phenomena which occur where the adsorbed humidity
shows capillary condensation as a main component of the adsorbent;
and
a corrugated material adhered to the sheet, the sheet, adsorbent,
and corrugated material forming a corrugated sheet, the corrugated
sheet being wound into a roll to form a cylindrical honeycomb
structure which is divided into a supply air zone and an exhaust
air zone, said cylindrical honeycomb structure being rotatable
slowly such that heat and humidity are continuously exchanged
between outer air and return air.
11. A total heat energy exchanger element as in claim 10, wherein
said adsorbent is rigidly adhered with an adhesive to the surface
of said laminate.
12. A total heat energy exchanger element as in claim 10, wherein
said adsorbent as particles is rigidly affixed with a binder
impregnated into said laminate.
13. A total heat energy exchanger element as in claim 10, wherein
said adsorbent is variously selected from the group consisting of
A-type silica gels, and RD-type silica gels and hydrophilic
zeolite.
14. A total heat energy exchanger element as in claim 12, wherein
said adsorbent comprises particles in the ratio of 5-30 g per 1
m.sup.2 laminate area.
15. A total heat energy exchanger element as in claim 10, wherein
said laminate is selected from the group consisting of metal,
plastic and ceramic fiber paper.
16. A total heat energy exchanger element as in claim 11, wherein
minute communicating pores are formed in the adhesive layer.
17. A total heat energy exchanger element as in claim 11, wherein
said adsorbent comprises particles in the ratio of 5-30 g per 1
m.sup.2 laminate area.
18. A filter material comprising:
a sheet;
an adsorbent selected from the group consisting of RD-type silica
gel, A-type silica gel, hydrophilic zeolite and active alumina, the
adsorbent having:
equilibrium isotherms for adsorption demonstrating no rapid rise in
relative humidity of more than approximately 40%, and
equilibrium isotherms for adsorption and desorption demonstrating
no hysteresis phenomena which occur where the adsorbed humidity
shows capillary condensation as a main component of the
adsorbent;
an adhesive adhering the adsorbent to the sheet;
a corrugated material adhered to the sheet, the sheet, adsorbent,
and corrugated material forming a corrugated sheet;
a boss around which the corrugated sheet is wound;
a generally circular surround member surrounding the corrugated
sheet wound; boss;
spokes extending from the boss to the surround member; and
rotation means for allowing the corrugated sheet, boss, surround
member and spokes to rotate together around an axis defined by a
center of the surround member.
19. A filter element as in claim 18, wherein the sheet is
aluminum.
20. A filter element as in claim 18, wherein the spokes extend
through the corrugated material.
21. A filter element as in claim 18, wherein there is an equal area
between adjacent spokes which corresponds to the area of a duct
through which inlet air travels and corresponds to the area of a
duct through which exhaust air travels.
22. A filter element as in claim 18, wherein the adsorbent is in
the form of a powder having a particle size less than 0.2 mm.
Description
BACKGROUND OF THE INVENTION
a. Field of the Invention
The present invention relates to a total heat energy exchanger
element which prevents odor transfer and the method of
manufacturing same, wherein adsorbent particles are rigidly fixed
to a sheet, such as metal, plastics, ceramic fiber paper and the
like, and the sheet is laminated and formed into a honeycomb
structure.
b. Description of the Prior Art
In U.S. Pat. No. 4,769,053, there is disclosed a method of
producing a total heat energy exchanger material by attaching a
composition comprising a molecular sieve to the surface of a sheet,
the molecular sieve having a plurality of pores of a diameter of
about 3 .ANG..
Examples of adsorbents used in the above-mentioned patent are
zeolite and synthesized zeolite. Among moisture adsorbents, silica
gel provides for high efficiency of total heat energy exchange and
can be obtained easily. Silica gels used as adsorbents include
A-type, B-type, RD-type, ID-type -and the like. A-type gel and
RD-type gel, with large surface areas and small capacities of
minute pores, have high efficiency of moisture adsorption in low
humidity, but they have low efficiency of moisture adsorption in
highly humid atmosphere. On the other hand, B-type and ID-type
gels, with small surface areas and large capacities of minute
pores, have high efficiency of moisture adsorption in highly humid
atmosphere, but have low efficiency of moisture adsorption in
conditions of low humidity (see the Handbook of Chemistry edited by
The Chemical Society of Japan, Applied Chemistry Parts, Part 1,
Process Section, Maruzen, pp. 256-257, Oct. 15, 1986), incorporated
herein by specific reference. FIG. 1 illustrates equilibrium
isotherms for water vapor adsorption of A-type, RD-type and B-type
silica gels manufactured by Fuji Davison Chemistry Co., Ltd.,
zeolite and an active alumina at 25.degree. C. (see Technical Data
90072084 of this company, incorporated herein by specific
reference). In this literature and others the type of silica gel as
a moisture adsorbent is not specified. But in order to cope with
hot and humid outer air during summer in Japan, B-type silica gel
with high desiccative capacity in high humidity is generally used
for multi-cylinder type dehumidifiers and for pressure swing
adsorption type dehumidifiers.
But the silica gels mentioned above adsorb not only humidity but
also various odors (gases). For example, in the summertime, hot and
humid outer air is passed through a supply air zone of a rotating
total heat energy exchanger element while return air from the room
controlled at proper temperature and humidity is passed through a
return air zone of the total heat energy exchanger element. Thus,
by the rotating total heat energy exchanger element the temperature
and the humidity of the outer air are lowered, and the resulting
air is supplied in the room. In such an operation in the low
humidity atmosphere, various odorous materials mixed in room air or
outer air are adsorbed and accumulated on part of the silica gel
particles in the total heat energy exchanger element.
In general, silica gel of any one of A-type, RD-type, ID-type and
B-type has the characteristic of adsorbing humidity in preference
to odorous materials. In the case of B-type silica gel, especially
when highly humid outer air passes through an operating total heat
energy exchanger element, such as in a rainy season or during a
shower when the relative humidity of the air suddenly increases,
the above-mentioned odorous materials adsorbed to and accumulated
on the rotating element are suddenly purged by the adsorption of
humidity contained in the outer air and these purged odorous
materials are mixed into the supply air and distributed in the
building causing the generation of odors in the rooms thereof,
which odors are sensed by the occupants.
SUMMARY OF THE INVENTION
The present invention was derived by confirming that there is no
generation of odor even if outer air of high relative humidity is
suddenly received by an operating total heat energy exchanger
element in which A-type or RD-type silica gel adsorbent or
hydrophilic zeolite or any other similar adsorbent is used. The
equilibrium isotherm for adsorption of water on the A-type or
RD-type silica gel adsorbent or hydrophilic zeolite or other
similar adsorbents does not rise suddenly and the equilibrium
isotherms for adsorption and desorption do not show hysteresis so
that equilibrium isotherms observed in adsorption and desorption
experiments are not different, i.e., moisture adsorbed on the
adsorbents does not cause "capillary condensation" in relative
humidity conditions of more than about 40%.
Minute pores of A-type silica gel and B-type silica gel will now be
compared. In B-type silica gel, as shown by the curve of B-type in
FIG. 1, adsorption capacity in high humidity atmosphere is
remarkably high and rapidly increases at around 50% relative
humidity when the relative humidity of the atmosphere is gradually
increased. The average diameter of the minute-pores of B-type
silica gel is around 70 .ANG. which is in the range of mesopores
(diameter of pore: approximately 20-500 .ANG.) and capillary
condensation easily occurs in pores in this range. This is
considered to be the result of the decrease of saturated vapor
pressure in minute pores of such a diameter (see S. J. Gregg and K.
S. W. Sing, Adsorption Surface and Porosity, Academic Press,
London, 1967, p. 160). In B-type silica gel, the curve showing the
equilibrium adsorption quantity in the case of gradually increasing
humidity from low level as shown in the drawing (adsorption curve
shown as "adsorption" in the drawing) and the curve showing
equilibrium adsorption quantity in the case of gradually decreasing
humidity from high level (desorption curve shown as "desorption" in
the drawing) do not correspond, and the so-called hysteresis
phenomenon is observed. This means that capillary condensation
occurs in this region. Among the five classifications of adsorption
isotherm types proposed by S. Brunauer et al. in J. Am. Chem. Soc.,
62, 1723 (1940), Type I contains A-type and RD-type silica gels,
alumina gel and hydrophilic zeolite with micropores of 4-6 .ANG.
diameter of FIG. 1. These adsorbents are of the type with minute
pore diameters not far larger than adsorbate molecular diameter.
Type II, under which the B-type silica gel of FIG. 1 falls, is the
type with minute pore diameters of wide range, and multi-molecular
laminar adsorption and capillary condensation phenomena occur.
Silica gel is porous material of various types with
ultramicropores, micropores, mesopores and/or macropores depending
on its manufacturing method. Average minute pore diameters of
A-type silica gel and B-type silica gel are about 22 .ANG. and
about 70 .ANG., respectively. But these gels also contain
micropores of diameters from 1-2 to 4-5 times as large as the
diameters of adsorbed molecules to a certain extent. In such small
micropores, strong dispersion forces act besides the adsorbing
forces by polarity between adsorbed molecules and micropores, and
the molecules to be adsorbed are strongly adsorbed to pores.
Therefore odorous materials and water molecules are partly
accumulated in such minute micropores. In the total heat energy
exchanger mentioned above, these odor and water molecules are
accumulated in the minute pores and adsorption and desorption are
repeated in a state of equilibrium inclined to the adsorption side.
If outer air humidity suddenly increases here, in the case of
B-type silica gel, its mesopores adsorb water vapor and are filled
with liquid water. That is to say, capillary condensation occurs
(cf., FIG. 2). In such conditions, there exist three phases, i.e.,
adsorption phase, solution phase and gas phase. Adsorbed materials
(odorous materials) are distributed among these three phases and a
binary equilibrium relationship exists, i.e., equilibrium between
the adsorption phase and the solution phase and that between the
solution phase and the gas phase. FIG. 2 shows a model of this
relationship. In the drawing a depicts the gas phase, b depicts the
solution phase (aqueous solution phase) and c depicts the
adsorption phase. The arrows designated by [A] and [B] show the
equilibrium relationship between a phase and b phase and that
between b phase and c phase, respectively. In FIG. 2, the adsorbed
molecules are limited to odor molecules and the water molecule
adsorption is omitted. Adsorbed odor molecules easily dissolve in
the solution phase and the odor materials in this aqueous solution
are further dispersed into the gas phase. Thus, binary equilibriums
of [A] and [B] are formed. Because gas phase a is a mobile gas
phase, concentration of the odor molecules in a decreases
immediately. Therefore, in order to keep the equilibrium odor
molecules in c transfer to b and then to a. In brief, odor
molecules are in an easily removable condition. Odor molecules are
removed with water molecules. That is to say, when capillary
condensation occurs due to the high humidity of the outer air,
accumulated odor molecules are mixed with supply air SA and
exhausted into a room immediately and the concentration reaches the
level the human sense of smell can detect some.
In the case of A-type silica gel and RD-type silica gel, the
average diameter of minute pores is around 22 .ANG., which is in
the range of micropores (diameter less than about 25 .ANG.). Pores
in this range have a strong adsorbing force and at the same time
mainly perform monolayer adsorption. There are only two phases,
namely, adsorption phase and gas phase throughout all the range of
relative humidity and equilibrium relationship between these two
phases. Therefore, as shown by the curves of A-type silica gel and
RD-type silica gel in FIG. 1, the quantity of water vapor
adsorption does not suddenly increase even if the relative humidity
increases and the hysteresis phenomenon is not observed and so
capillary condensation scarcely occurs. That is to say, as there is
no liquid water phase which dissolves adsorbed odor molecules
easily, unlike B-type silica gel mentioned above, odorous materials
are never suddenly purged by adsorption of outer air humidity, and
this means that the odor generation is too small to be perceived by
the human sense of smell.
From the foregoing, it will be apparent that the present invention
relates to a method of manufacturing a total heat energy exchanger
element preventing odor transfer and the total heat energy
exchanger element obtained by this method. The characteristic of
the present invention is to use adsorbents whose equilibrium
isotherms do not rise rapidly from low humidity to high humidity,
and whose equilibrium isotherms for adsorption and desorption do
not show hysteresis so that equilibrium isotherms observed in
adsorption and desorption experiments are not different, and in
which the humidity does not cause "capillary condensation" in cases
of relative humidity more than about 40%. For example, the
adsorbents such as the above-mentioned A-type silica gel or RD-type
silica gel, or hydrophilic zeolite having no mesopore capable of
showing capillary condensation or the like can be used.
Particulates of these adsorbents are fixed rigidly to the sheet
surface of a metallic sheet or plastic sheet or ceramic fiber
paper, etc. in the ratio of 30 g/m.sup.2 at the greatest, and the
sheet is laminated and formed into a honeycomb structure.
BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 is a graph showing equilibrium isotherms for adsorption of
A-type, RD-type and B-type silica gels, alumina gels and
zeolite;
FIG. 2 is a diagram showing how odor molecules are distributed
among three phases brought about by capillary condensation;
FIG. 3 is a schematic diagram illustrating a method of
manufacturing the total heat energy exchanger material;
FIG. 4 is a perspective view of a single-faced corrugated
sheet;
FIG. 5 is a perspective view of a rotary-type total heat energy
exchanger element;
FIG. 6 is a vertical section view of a rotary-type total heat
energy exchanger;
FIG. 7 is a graph showing the odor transfer rate and odor transfer
amount of total heat energy exchanger elements;
FIG. 8 is a graph illustrating the testing conditions of total heat
energy exchanger elements;
FIG. 9 is a graph showing the latent heat exchange efficiency of
total heat energy exchanger elements using various amounts of
silica gel; and
FIG. 10 is a graph showing the latent heat exchange efficiency of a
total heat energy exchanger element using a blowing agent.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Example No. 1
FIG. 3 schematically illustrates a device used to manufacture the
total heat energy exchanger element of the present invention. In
the drawing, reference numeral 1 designates a vessel of adhesive 2.
The reference numeral 3 designates squeezing rollers, while the
reference numeral 4 designates a vessel containing particulates 5
of A-type and/or RD-type silica gels. Guide rollers are shown as
designated by reference numeral 6, suction ducts are designated by
reference numeral 7 and the reference numeral 8 designates a
heater.
To both surfaces of a 30.mu. thick aluminum sheet 13, a suitable
amount of adhesive 2, consisting of polyvinyl acetate, is applied
by adjusting the gap between squeezing rollers 3. The sheet 13 is
fed into the vessel 4 containing the adsorbent particulates 5, and
A-type and/or RD-type silica gel powder 5 of particle size below
0.2 mm adheres to both sides of the sheet 13 to temporarily fix the
A-type and/or RD-type silica gel powder of around 20 g in total of
both sides per 1 m.sup.2 of the sheet surface area. Particulates of
silica gel which do not adhere to the sheet 13 are removed by
exhausting air through its ducts 7, 7.
The sheet 13 is then heated at a high temperature of
100.degree..about.250.degree. C. by the heater 8 for a short time
to completely dry and harden the adhesive and at the same time to
form many communicating pores from the sheet surface to the
adhesive layer surface by emitting gas and other impurities
adsorbed in the A-type or RD-type silica gel minute pores and
volatile ingredients in the adhesive so that adsorption capacity of
the A-type or the RD-type silica gel is not impeded. In this manner
the aluminum sheet 15 of a total heat energy exchanger element is
produced.
The total heat energy exchanger material thus obtained is
corrugated, as shown in FIG. 4, and the flat sheet 15 and the
corrugated sheet 16 are alternately adhered and laminated, and
wound around a boss 17, as shown in FIG. 5, to a desired size to
form a cylindrical structure with many small channels 18 between
both end surfaces. Several grooves are cut in a radial direction on
both end surfaces of the cylinder, and reinforcing spokes 19 are
fitted in place and rigidly adhered. Outer circumferential steel
plate 20 is wound around the circumferential surface. One end of
each of the spokes 19 is rigidly secured to both end surfaces of
the boss 17 and the other end thereof is secured to the outer
circumferential steel plate 20 by an appropriate means such as
bolting. Belt plates 21 are wound around both end edges of the
outer circumferential steel plate 20 and rigidly fixed The
connecting belt plates 22 are thereafter installed between the belt
plates 21.
Example No. 2
An adhesive 2 consisting of polyvinyl acetate is mixed with about
20-40% of A-type and/or RD-type silica gel particulates and the
adhesive is applied on both surfaces of the sheet 13. By rapidly
heating this sheet to high temperature with heater 8, gas and other
impurities adsorbed to silica gel are desorbed and the adhesive
hardens. At the same time many minute communicating pores are
formed in the adhesive layer. That is to say, silica gel
particulates mixed in the adhesive layer adsorb and desorb humidity
in the outer air through the above-mentioned communicating pores.
The total heat energy exchanger material thus obtained is
corrugated and laminated as in Example 1 to obtain a total heat
energy exchanger element. A chemical blowing agent may be mixed in
the adhesive.
Example No. 3
Into adhesive 2, consisting of polyvinyl acetate, about 20-40
weight % of A-type and/or RD-type silica gel or active alumina
particulates and about 5 weight % of fine powder of sodium hydrogen
carbonate or ammonium carbonate as chemical blowing agent are
mixed. The adhesive is applied on both surfaces of the sheet 13. By
rapidly heating the sheet to high temperature with the heater 8,
chemical blowing agent in the adhesive decomposes and generates
bubbles while the gas adsorbed to silica gel is desorbed and the
adhesive hardens. At the same time many minute communicating pores
are formed in the adhesive layer. That is to say, the buried silica
gel particulates are able to adsorb humidity in outer air. The
total heat energy exchanger material thus obtained is corrugated
and laminated as in Example 1 to obtain a total heat energy
exchanger element.
Example No. 4
Adhesive 2 consisting of acrylic resin is applied on both surfaces
of the sheet 13. A mixture of A-type or RD-type silica gel
particulates and hydrophilic zeolite particulates having little
mesopores and hardly causing capillary condensation in a proper
ratio is temporarily fixed on both surfaces of sheet 13 as in
Example 1 and heated to high temperature with heater 8 to harden
the adhesive.
In the above examples, the sheet material may be properly chosen
from metals such as aluminum alloy, stainless steel, copper, brass,
aluminum, plastics such as polyvinyl chloride, polypropylene and
polyester, ceramic fiber paper and nonflammable paper, etc. which
can be corrugated. A humidity adsorbent which does not promote odor
transfer, i.e., hardly causes capillary condensation because of
little mesopores such as the above-mentioned active alumina and
hydrophilic zeolite is used with A-type and/or RD-type silica
gel.
Sheet 13 consists of paper consisting mainly of inorganic fiber
incapable of being ignited by hot air, for example, 0.1-0.3 mm
thick paper mainly consisting of ceramic fiber, which contains
50-70% of ceramic fiber, 5-10% of glass fiber both with about 5.mu.
diameter and 1-5 mm length, 30-5% of pulp and 10-20% of binder and
paper strength reinforcing agent, or paper mainly consisting of
pulp made nonflammable and reinforced by aluminum hydroxide.
The adhesive 2 used is polyvinyl acetate, epoxy resin, silicone
resin and acrylic resin, etc. The inorganic binder (reinforcing
agent for paper) is silica sol, alumina sol and the like.
As shown in FIG. 6 the cylindrical total heat energy exchanger
element obtained in the above examples is held rotatably and
operably mounted by a shaft 23 and supported within the casing 24.
Ducts 26, 27 and 28, 29 are provided so that both end surfaces of
the element 25 are divided into the inlet air zone, the supply air
zone, the return air zone and the exhaust air zone. The element 25
is rotated at the rate of about 16 r.p.m. Inlet air (OA) and return
air (RA) define the juncture of total heat energy exchange between
both airs through the total wall surface of small channels 18 of
the element 25 to supply supply air (SA) and to exhaust exhaust air
(EA)
Silica Gel PA-9035A of Fuji Davison Chemicals Co., Ltd. was used as
the A-type silica gel and also the RD-type silica gel was used.
Zeolum A-4 of Tosoh Co., Ltd. was used as the hydrophilic zeolite,
and Silica Gel PA-9035B of Fuji Davison Chemicals Co., Ltd. was
used as the B-type silica gel in a contrasting example. Their
particle sizes were all around 200 mesh. According to Example 1,
the above four kinds of adsorbents were rigidly adhered to both
sides of 30.mu. thick four aluminum sheets in the ratio of 16 g in
total of both sides per 1 m.sup.2 of sheet surface area,
respectively. These sheets were corrugated so that the wave length
P is 4.2 mm and the wave height is 2.2 mm, respectively (cf. FIG.
4), and four kinds of total heat energy exchanger elements of 200
mm element width t (cf. FIG. 6) were manufactured. Under the
condition described below an odor transfer test in each element was
performed. As shown in FIG. 8, the total heat energy exchanger with
each element was operated at a speed of revolution of 15 r.p.m.
1 Air of 25.degree. C. temperature and of 42% relative humidity
containing 30 ppm of toluene as the odor substance was sent in as
return air RA for 30 minutes, so that the moisture and toluene were
adsorbed in the element, and then under the same conditions air
containing no toluene was sent in continuously.
2 On the other hand outer air of 33.degree. C. temperature and of
40% relative humidity was sent in for 30 minutes, and thereafter,
the transfer rate (%) and the transfer amount (ppm) of toluene into
supply air SA.sub.2 brought through the element were measured. The
result is shown in points on the line of relative humidity of 40%
in FIG. 7.
3 While outer air of 33.degree. C. temperature and of 65% relative
humidity was sent in, the transfer amount (ppm) and transfer rate
(%) of toluene into the supply air SA.sub.3 were measured. The
result is shown in points on the line of relative humidity of 65%
in FIG. 7.
4 While outdoor air of 33.degree. C. temperature and 80% relative
humidity was sent in continuously, the transfer amount (ppm) and
transfer rate (%) of toluene into supply air SA.sub.4 were
measured. The result is shown in points on the line of relative
humidity of 80% in FIG. 7.
The transfer ratio (%) of the drawings is calculated from toluene
concentration (ppm) in supply air divided by toluene concentration
(ppm) in return air. As seen from the drawings, when outer air of
33.degree. C. and 80% relative humidity was treated, in the case of
B-type silica gel, odor was perceived at transfer amount of about
5.5 ppm, and on the other hand in the case of A-type and RD-type
silica gels and hydrophilic zeolite, transfer amounts were less
than 0.4 ppm and odor was scarcely perceived. These toluene
concentrations were measured by Gas Chromatograph GC-14A supplied
by Shimadzu Corporation.
When methyl mercaptan and trimethylamine were tested as other odor
materials, the odors could not be perceived by the human sense of
smell. This test was performed by several people.
Particularly in Japan, when humidity varies greatly as in the rainy
season, odor generation often occurs from a total heat energy
exchanger element. That is to say, it is possible that, in the case
of using B-type silica gel as shown in FIG. 7, and other adsorbents
showing capillary condensation, odorous material in return air is
adsorbed by an element and transferred into supply air to exceed,
in concentration, the level perceivable by the human sense of smell
(in the case of toluene 0.48 ppm, cf., Environmental Pollution and
Poison, Dangerous Objects (Organic Materials) by Hiroshi Horiguchi,
Sankyo Publishing Co., Ltd., p. 458, Jun. 25, 1971). On the other
hand, in the cases of A-type and RD-type silica gels and
hydrophilic zeolite, there is no possibility of odorous substances
transferring into the supply air to exceed, in concentration, the
level perceivable by the human sense of smell (less than 0.48 ppm).
For example, when air containing various odorous gases generating
from the kitchen and lavatory of a building, and from human bodies,
is passed as return air through a total heat energy exchanger for
total heat energy recovery, the transfer of odorous gases into the
supply air via the total heat energy exchanger can be prevented for
the most part. This is due to the adsorption characteristics of
A-type and RD-type silica gels and hydrophilic zeolite. That is to
say, as shown in FIG. 1, even if the air humidity increases, the
desiccative rate does not increase so much that odor substances
adsorbed in the total heat energy exchanger element do not come to
be suddenly purged. In other words, when the total heat energy
exchanger is working and adsorbing moisture and odorous substances
at the same time, the adsorption characteristic does not suddenly
increase, as shown by the equilibrium isotherms for adsorption in
FIG. 1, even if the relative humidity of the outer air suddenly
increases. Therefore, desorption of odorous substances adsorbed is
extremely slow and the human sense of smell does not perceive odor.
In this case, it is also possible to increase the latent heat
exchange efficiency in conditions of high humidity atmosphere by
mixing an appropriate amount of B-type silica gel, i.e, in the
level of amount that odor in supply air SA is not perceived by a
person even if the humidity suddenly increases, for example, in the
ratio of 10-20% to the total amount of adsorbent.
FIG. 9 shows the relationship between the fixed amount of A-type
silica gel and the latent heat exchange efficiency (n.sub.x) when
the single-faced corrugated sheet has 4.2 mm of wave length P and
2.0 mm of wave height h and a cylindrical element, i.e., a rotor,
has 200 mm of width t and 15 r.p.m. of rotation speed. In the
drawing, the abscissa shows air velocity (m/s) of feed air and
return air at the element inlet. As seen in the drawing, when the
fixed amount of A-type silica gel is 5 g/m.sup.2 and the air
velocity 2 m/s, the efficiency is 67%. When the air velocity is 3
m/s, n.sub.x is as low as 60%. As the fixed amount increases from
10 g/m.sup.2 to 15 g/m.sup.2 and to 20 g/m.sup.2, the efficiency
increases. When the fixed amount is 30 g/m.sup.2, the efficiency is
80% at the same air velocity of 3 m/s, and the efficiency increases
little even if the fixed amount is further increased. Here the
conditions are: outer air temperature is 33.degree. C., the
relative humidity is 55%, the return air temperature is 25.degree.
C. and the relative humidity is 70%.
As the total heat energy exchanger element of the present invention
is obtained, as described above, by adhering or impregnating
particulates of A-type, RD-type silica gel, activated alumina or
zeolite whose equilibrium isotherms for adsorption do not rise
rapidly in relative humidity more than about 40%, and which have no
hysteresis phenomena, i.e., adsorbents in which adsorbed humidity
does not cause capillary condensation as a main component of
adsorbent to the sheet surface with adhesive or binder, and by
laminating this sheet to form a honeycomb structure, it has the
effect of preventing odor generation in the room. In other words,
various odor substances contained in return air are adsorbed by the
adsorbent in the element while driving, but these odorous
substances adsorbed are not purged by adsorption of water vapor at
high relative humidity, and are not transferred into the supply
air.
Also, in the manufacture of the total heat energy exchanger element
of the present invention, adhesive or binder is applied on the
surface of the sheet of metals or plastics. Then particulates of
adsorbents mentioned above are attached on the adhesive or binder
layer and the sheet is heated for a short time at a high
temperature of 100.degree.-250.degree. C. By this process, the
adhesive or binder hardens completely and at the same time the
adsorbent particulates are fixed with one part of each particulate
buried in the adhesive or binder layer and the other part exposed.
Thus, total heat energy exchange efficiency is performed for a long
time without the danger of adsorbent particulates falling off from
the sheet surface by operation or washing of the total heat energy
exchanger element.
When A-type and/or RD-type silica gel particulates are mixed in the
adhesive or binder as shown in Example 2, or when A-type and/or
RD-type silica gel particulates and chemical blowing agents are
mixed in the adhesive or binder as shown in Example 3, and when the
adhesive or binder is applied on the sheet surface and hardened by
heating, gases adsorbed to silica gel mixed in the adhesive or
binder are desorbed to form many minute communicating pores in the
adhesive or binder layer, or the chemical blowing agent further
decomposes and blows to form many minute communicating pores from
the sheet surface to the adhesive or binder layer surface. Thus,
the adsorbent particles buried in the adhesive or binder layer
effectively function through the communicating pores. In the latter
case, when A-type silica gel was fixed in the ratio of 15
g/m.sup.2, 84% of the latent heat exchange efficiency was performed
at a flow velocity of 2 m/s, as shown by the solid line in FIG. 10,
which is about 3% higher than where no chemical blowing agent is
mixed in the adhesive, as shown by the dashed line in FIG. 10.
Adding hydrophilic zeolite as a component of adsorbent (Example 4)
has the effect of increasing the latent heat exchange efficiency of
the total heat energy exchanger element in treating low humidity
air and without the possibility of increasing the odor transfer
ratio. However, in this case the zeolite used should be one with
few mesopores which causes little capillary condensation.
Although a preferred embodiment of the present invention has been
described, it is to be understood that other embodiments may exist
and changes made without departing from the spirit and scope of the
invention.
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